class A {
  constructor(a) {
    this.a = a;
  }
}

class B extends A {
  constructor(a, b) {
    super(a);
    this.b = b;
  }
}

let b = new B(1,2)

console.log(b.__proto__)
console.log(B.prototype)
console.log(B.__proto__)
console.log(A.prototype)
console.log(A.__proto__)
// B {}
// B {}
// [Function: A]
// A {}
// [Function (anonymous)]
